The invention relates to a method of recording information on a record carrier having a magneto-optical recording layer, a pattern of magnetic domains having a first and a second direction of magnetization being formed in the recording layer by scanning the recording layer with a radiation beam in order to temporarily heat the recording layer locally, the heated portions of the recording layer being exposed to a magnetic field which is directed substantially perpendicularly to the recording layer and which is generated by means of a coil, the coil being energized with an energizing current which is modulated in conformity with an information signal.
The invention further relates to a magneto-optical recording apparatus for recording information on a record carrier having a recording layer of a magneto-optical material, which recording apparatus comprises an optical system for scanning the recording layer by means of a radiation beam, a coil for generating a magnetic field in the scanned portion of the recording layer, which field is directed substantially perpendicularly to the recording layer, an energizing circuit for generating an energizing current in the coils, which current is modulated in conformity with an information signal.
Such a method and apparatus are known from European Patent Specification EP-A No. 0,230,325. In the known method a constant intensity laser beam is aimed at a rotating magneto-optical disc by means of an optical system to image a radiation spot on the magneto-optical disc. The portion of the magneto-optical disc which is scanned by the radiation spot is heated to substantially the Curie temperature. The heated portion is magnetized by means of a coil which has a core of a soft magnetic material and is arranged opposite the optical system, at the other side of the rotating magneto-optical disc. The coil is energized with an alternating current modulated in conformity with the information signal, is such a way that the heated portion is magnetized in a direction which depends on the instantaneous polarity of the alternating current. The magnetization is preserved after cooling. In this way a pattern of magnetic domains representative of the information signal is formed in the recording layer.
This recording method has the advantage that a previously formed pattern of magnetic domains can be overwritten. In order to achieve an adequate recording velocity a small low inductance coil is used, which is energized with a comparatively large energising current. A problem which then occurs is the substantial heat dissipation in the coil, the coil core and the electronic drive circuitry. This heat dissipation is therefore a restrictive factor in raising the recording velocity and/or increasing the magnetic field strength, for example in order to increase the distance from the coil to the recording layer.